Solvent extraction and separation of samarium from transition and rare-earth metals using phosphonium ionic liquid Cyphos IL 104

Abstract

The objective of this work is to investigate the extraction behavior of samarium from chloride medium using trihexyl(tetradecyl)phosphonium bis-2,4,4-(trimethylpentyl)phosphinate (Cyphos IL 104), and separation efficiency of samarium in presence of other rare-earth and transition metals. It is then extended to Sm-Co separation from secondary magnetic waste. The extraction efficiency of Cyphos IL 104 is studied in detail by varying the key extraction parameters like shaking time, aqueous phase pH, ionic liquid, metal and chloride ion concentration, type of diluents, and temperature of aqueous phase. Quantitative extraction of 0.002 mol/dm(3) Sm(III) has been found using 0.02 mol/dm(3) Cyphos IL 104. Extraction equilibrium of samarium with Cyphos IL 104 is explained using the slope analysis method and FT-IR study. NaCl is used as a salting out agent that increases the samarium extraction. Toluene is found to be best diluents for dilution of Cyphos IL 104. The stripping efficiency is observed to be quantitative with 20% H2SO4 and 5% HNO3. The extraction process is endothermic in nature revealed from the temperature variation study. The investigation of samarium extraction in the presence of transition metals has been conducted and highest separation factors of 189.5 and 158.5 are obtained for Sm/ Co and Sm/Ni, respectively, at initial pH 3.0. [GRAPHICS] .